Artificial respirator



May 2, 1933. P, DRINKER l-:r AL 1,906,844

ARTIFICIAL RESPIRATOR Filed Nov. 27. 1931 4 Sheets-Sheet l fo w r W" "Hm gli@ i151". Ln WF (y Q d! m m N N z z w f 1 A e n K au May 2, 1933. P, DRINKER Er AL ARTIFICIAL RESPIRATOR Filed NOV. 27, 1951 4 Sheets-Sheet 2 ENToR May 2, 1933. P, DRINKER ET AL ARTIFICIAL RESPIRATOR Filed Nov. 27. 1931 4 Sheets-Sheet 3 May 2, 1933.

P. DRINKER ET AL 1,906,844

ARTIFICIAL RESPIRATOR Filed NOV. 27, 1931 4 Sheets-Sheet 4 Eby/3 Y' f- 85 Y\\ \1 E l l l Patented May 2, 1933 UNITED sTATes PATENT OFFICE PHILIP DRINKEB AND LOUIS AGASSIZ SHAW, OF BOSTON, HASBAUHUSETTS. ASSIGNORS, BY HESNE ASSIGNMENTS, TO WARREN E. GOLLINS, WARREN E. COLLINS, JB., AND WALTER G. HIOX, ALL F BOSTON, MASSACHUSETTS ARTIFICIAL RESPIRATOB Application nled November 27, 1931.

The present invention relates to apparatus for use in aiding or producing respiration. Emergency cases of drowning, lgas isoning, electric shock and the like have ong been treated by artificially inducin respiration to 'ventilate the lungs unti the patient recovers suiicientl to `breathe naturall By the use of t e lapparatus descri d in our'co ending application Ser. No. 380,271 filed ul 23, 1929, it has been possible within the ast two ears to use artificial respiration successful y in pathological cases of poliomyelitis, dipht eritic paralysis, drug poisonlng, and asphyxie from other causes where artificial respiration complete or in part, for prolonged periods sometimes extending over several months has been necessar.

The present invention as for an object to provide a respirator which will be more eiiicient and will aiford greater comfort for the patient and greater ease for the nurses and doctors in carin for a patient and esecially so in case o prolonged treatment.

he invention aims, for example to make provision for rotating and/or for t11tinglongitudinally the bed on which -the patient reclines in order that a restful variation of position or a position dictated by the requirements of medical therapy 4may be obtained.

Another object of this invention is to provide an apparatus into which the nurse may extend her hands and arms for the purpose of chan in the bed giving the patient a bath or t e i' e, without removing the patient from the respirator.

Another object is to make provision for access to the interior of the caslng for treat ment and for attention to the comfort and convenience of the patient or to provide for the easy introduction of abcd pan, urinal or other device, all without materially interru tin res lration.

A urt er o ject is to provide a unitary, com act apparatus that can be easily and quic ly moved to the place of use.

It is also an object of the invention to provide an improved method of producing artificial respiration,

Serial No. 577.510.

With these and other objects in view the invention provides in the preferred form, a unitar self contained apparatus com rising a su tantially air-tight casing in w ich the `patient may recline in a comfortable position with the head and neck projectinr out through the end wall of the casing, an means for periodically varying the air pressure in the casing to cause or to aid respiration. The casin is preferabl mounted to tilt longitudina y and laters. ly as a convenient means for changing the osition of the patient to avoid congestion o the lungs and generally to add to the comfort of the patient. Provision is also made for access to the casing to permit attending to the comfort of the patient without interfering with regular respiration.

The nature and objects of the invention will be better understood from a description of a particular illustrative a paratus for the urpose of which description reference shou d be had to the accompanying drawings forming a part hereof and in whlch,

Figure 1 is a side view of a respirator constructed in accordance with the invention showing the casing tilted to incline the head of the `patient. downwardly,

Figure 2 is a detail view showing the forward end of the casing in horizontal position, the body support retracted from the casing and the leg member locked in extended vertical position,

\ Figure 3 is a front view of the device showing the casing rotated laterally on the carriage,v

Figure 4 is a detailed sectional view of the arm port taken on the line 4 4 of Figure 1,

Figures 5 and 6 are detail views of the rubber arm sealing collar and the rubber closing iiap respectively,

Figure 7 is a detail sectional view of the neck sealing collar taken on the line 7-7 of Figure 3,

Figure 8 is an end view of the air pump and connections taken on the line 8-8 of Fi re 1,

igure 9 is a detail view showing rein-l Figure 13 is a detail view of the same taken on the line 13--13 of Fi re 12 Figure 14 is a detail sectiona view showing the rotatable valve member in a different position taken on the line 14-14 of Fi re 15,

igure 15`is a detail sectional view taken on the line 15-15 of Figure 14, and,

Figure 16 is a detail sectional view similar to Figure 14 but showing the rotatable valve member rotated through an angle of 180.

In the apparatus shown for the purpose of illustrating the principles of the invention, a atient receiving casing 5 is mounted on a wiieeled carriage 6 on which carriage is also mounted aY self-contained power plant 7, arranged to periodically vary the pressure in the casing to induce and maintain artificial respiration. The casing 5, may convenientlly be made of metal with the seams wel ed and all other joints packed to render the casing substantially air-tight within the ran e of pressures at which it is to be used, which ressures, positive or negative, are not like to exceed 70 centimeters of water. A bo y support or bed 10, is provided to receive the bod of the patient within the casing with the ead and neck projecting through the removable front end wall 11. This end wall conveniently may be carried as a rigid part of the body support which body support is movable into and out of the casing on rollers 14, carried by the body support.'

For pathological reasons it 1s often desirable to tilt the tient laterally from time to time and pre erably also longitudinall Obviously it is also more comfortab e for the patient to rest in different positions. In the apparatus shown the desired results are accomplished by tilting the casing instead of moving the patient relative to the bed or tilting the bed laterally and/or longitudinally within the casing. The casin in the arrangement shown, 1s mounted `or movement on the carriage in two directions; that is to say, it is tiltably mounted on a transverse horizontal axis so that it can be tilted longitudinally to a position in which the feel? O the Pall may be either hi her or lower than his head and it is rotata ly mounted in order that it may be tilted laterally to change the position of the atient laterally. As shown, the desire tilting movement is obtained by means o f a yoke 15 which is trunnioued to the carriage permit movement about the transverse horizontal axis 16 and the casing is rotatably mounted in this arcuate yoke to permit as much rotation about a longitudinal axis as is considered necessary or desirable. The casing is shown, as carry- 1n an arcuate rail 17 suitably enga ing ro 1ers 18, in the yoke 15, the length o the rail, though not a complete circle, being such as to permit the desired rotation.

In order to secure the casing in longi- 'tudinally tilted position a clamp 20 is carried at its rear end and engages an arcuate o r other suitably shaped brace 21. The clamp 20 is shown as rotatably connected to the casin on a stud 22 in order not to interfere wit the lateral tilting of the casing about its longitudinal axis and as ca ing a pawl 23 engageable with notches 4 on the sector 21. An suitable means may be rovided for holding the casing in latera y tilting position. As shown a s lit clamp 19 engaging the ange of the rai 17 is tightened by the hand wheel 19a and its shaft.

When the atient is to be introduced into or removed rom the casing, the casi is adjusted to horizontal position, both terally and longitudnall and the body support is retracted as in icated in Figure 2. Ihe forward end of the body support and the forward end plate 11 of the casing which is rigid therewith may be supported by a pair of telescopin or otherwise retractable legs 25 carrying ro 1ers 26. These adjustable or retractable legs are hinged at 27 in order that they may be folded out of interfering osition when the forward end of the casing 1s tilted downwardly as indicated in Figure 1, but they may be latched in vertical extended position as indicated in Figure 2 by means of a latch 28 engaging a catch 29.

Suitable means is provided for preventing undue movement of the patient laterally on the bed when the casing is tilted. It is not necessary to shape the bed and mattress to extend upwardly on each side of the patient unless the casing is to be rotated so far that he actuall lies on one side. Accordingly we have own merely retainin rails 37 at each side of the bed Ato prevent s iding of the mattress or bed clothes or the atient.

The front end plate 11 can e clamped in closed position against the casing, by the clamps 40 or other suitable clamping means, the joint being suitably acked to insure an air-tight connection. he head of the patient projects through the forward end plate and rests upona vertically adjustable lll and removable head rest 41. Between the neck of the patient and the casing an airtight seal is formed b a fiexible rubber collar 42, several sizes ofI which may be supplied with each machine to suit large and small persons. The collar has a central aperture 43 to receive the neck of the patient and is clamped against the forward end plate by means of a ring 45 and four clamps 46 engaging said ring. The clamps 46 may conveniently be pivotally mounted on headed bolts 47 and may be adjusted to tighten the ring 45 by means of thrust screws threaded through the outer ends of the clamps and bearing against the casing wall.

The rubber collar is made relatively thin toward its center portion but not so thin as to be readily torn in handling and its outer portion is made thick enough to withstand the effect of the clamping rin Immediately around the aperture a s ight bead 48, shown exaggerated in the drawings, is preferably formed to prevent tearing. Vhen applying the collar, it is stretched sufficiently to slip over the head of the patient and when the patient is in a comfortable position with his head on the head rest, the edges of the collar are pulled radially outward stretching the collar sufficiently to prevent undue tension on the neck and the clamps are tightened to hold the collar in this comfortable but leak-proof position. The rubber collar may be relied upon to resist the pressures occurring during the operation of the apparatus or if desired shutter plates may be used to reinforce the rubber diaphragm either on the inside only or both on the inside and outside. The shutter plates may be of any desired form such as commonly used in photographic light shutters or such other construction as may be effective to limit the bulging of the fiexible rubber sheet during the periodic variations of pressure within the casing. As shown in Figure 9, adjustable shutter plates 49 are shown as movable toward and from the center of the aperture in the front plate and sufficiently close to the inner face of the rubber collar to reinforce the same and prevent undue bulging inwardly. These shutter plates may be adjusted to such position as 1s comfortable for the patient. Ordinarily it is sufficient to rovide the shutter plates to support the ru ber collar against bulging inwardly since the positive pressures likely to be used are not sufficient to cause undue bulging of the collar outwardly.

The forward end of the casing as shown slopes upwardly and backwardly at an angle of substantially 75 to the longitudinal axis of the casing in order that the collar when secured fiat against the end wall may engage the neck of the patient close to the chest, this arrangement being ordinarily more comfortable and permitting more convenient access to the front of the neck in case treatment or operation is desirable. This arrangement of sloping the whole end of the case is more convenient in manufacture than an arrangement in which the collar is set at an angle to the end wall and provides greater comfort for the patient enabling him to tilt and move his head more freely than would a vertical casing wall.

The casing is shown as provided with a number of arm ports to permit access to the interior for attention to the patient, such as changing bed clothes, bathing, alco hol rub and the like, without interfering with the breathing of the patient. Each arm port is closed by means of a rubber collar 56 having a central aperture 57 which rubber collar is designed to form an airtight seal about the arm of the operator when inserted into the casin or the arm of the patient if projected out t rough the casing. The position of these arm ports will be arranged as the convenience of the operator and atient may require. VA second rubber disc ormed to Aprovide, a fiap 60 is positioned against the outer face of the rubbersealing collar and in practice will form an airtight seal, which is effective if positive pressure is not used Vin the casing. A hinged rigid cover 61 preferably having a transparent window therein may also be added to afford a locked closure.

Conveniently adjacent to the arm )orts is placed a larger port or ports 63 o a size to permit insertion of a bed pan, urinal or other apparatus in position to be received in a hand inserted tirough one of the arm ports. This port is closed by a suitable hinged door 65 packed to provide an airtight seal. The door can be opened when the vacuum in the casing is released to permit exhalation anarticle inserted and the door quickly ciosed without material interference with the breathing of the patient.

At theltop of the casing a suitable fitting 66 permits the introduction of a rubber tube for use in giving an enema or for any other desired purpose. The same fitting can be used for introducing a thermometer into the casing and for other purposes.

The power plant 7 for periodically causing fluctuation of pressure within the casing is mounted on the lower portion of the wheeled carriage beneath the casing to provide a complete unitary apparatus which can be conveniently moved to the point of use. This is particularly important when the device is used as an emergency respirator for cases of asphyxia due to accidental shock, gas poisoning or the like.

The power plant comprises a motor 7 directly connected to an air pump 71 the suction side of which is connected to the conduit 72 and the pressure side 0f which is connected to a conduit 73 which dischar es through a muler 74 and discharge out et 75 to atmosphere. The suction conduit 72 leads to a valve 76 from which a flexible conduit 77 leads to the casing 5. The valve 76 is shown iudetail in Fi res 12 to 16. This valve is rotatablge driven from the motor shaft and may so connected alternatively that air is exhausted from the 1 casing at timed intervals. As shown the suction conduits 72 leads into the end of the valve casing, and the conduit 77 is connected by a Y connection 79 leading into the valve casing near the opposite ends thereof. A three way valve 80 o ens either leg of the Y connection to the exible conduit 77. One end of the rotatable valve member 81 is provided with two ports 82 and 83 on opposite sides, either of which ports cominv' opposite the port 84 at the top o the va ve casinglwill open connections between one leg of t e Y connection and the suction conduit 72. At 90 to these ports 82 and 83 are ports 85 and 86 which are closed from the suction conduit but which can open connection between the port 84 and the port 88, thus permitting entrance of air through the port 88 and release of the partial vacuum in the casing 5, if the valve 80 is adjusted to make this end of valve 76 operative.

The rotatable valve member 81 is provided at its other end with one suction port and one inlet ort 90 and 91 respectively which alternate y register with the port 92 leading to the second leg of the Y connection and at their opposite outlets make connection respectively with the suction line 72 and air port 88.

If for any reason, it is desired to so operate the apparatus as to provide in the casing alternately sub-atmospheric and superatmospheric, instead of merely sub-atmospheric and atmospheric pressures, a length of ose can be connected between the outlet 75 of the mutiler 74 and the port 88 of the valve 76 as indicated in dotted lines in Figure 1. By this arrangement each time that the ports of the valve 76 are suitably registered superatmospheric pressure will be produced 5 in the casing 5 instead of merely permitting the release of the partial vacuum and restoration of the inside of the casing to atmospheric pressure.

This arrangement of the valve 76 actuated by the motor 70 and the three way valve 8O which can be adjusted to make one end or the other of the valve 76 operative to provide for two different rates of variation of ressure within the casing as for example 6 15 and 30 per minute, and which will cause the patient to inhale and exhale either 15 times per minute or 30 times per minute. It has been found in practice that the provision of these two available rates for respiration is generally suiiicient for the average tpatients and the motor can be run at a. preetermined standard s eed. However, if

further variations are esired the s eed of the motor can be varied b means o a suitable rheostat to give any esired rate of resiration.

The extent of the vacuum produced in the casing can be controlled by means of a valve 95 located in a shut path between the inlet and outlet 73 of the pump 71 (Figure 8) which valve 95 may be partially opened to permit more or less by-pass of air between the suction and delivery sides of the pump 71. A safety valve 98 may be connected to the suction conduit 72 to automatically prevent excessive vacuum.

Wfe have found that the use of alternate vacuum and atmos heric pressure in the casing 5 is more com ortable and less tiring on the average patient than the use of superatmospheric pressures. The degree of vacuum preferred is between l5 and 3() centimeters of water on the manometer.

By the use of alternate vacuum and atmospheric pressures it is ossible to keep patient breathing by arti cial respiration for indefinitely long periods of time (some patients having been kept in the respirator for as long as six months without tiring or in any manner injuring the patient as the vacuum merely causes expansion of the lungs by the air which enters through the mouth and nose ofthe patient and the restoration of atmospheric pressure inside the casing causes contraction of the lungs and exlialation of part of the previously inhaled air).

All this is without unnatural pressure, niechanical or super-atmospheric in any form and hence the apparatus does not tire or exhaust the patient but on the other hand relieves him from the strain and effort of breathing, which in the case of paralysis of the intercostal muscles, becomes very di cult and often impossible, resulting in death of the patient.

The use of alternate, sub-atmospheric and atmospheric pressures avoids congestion of the blood in the head and neck of the patient, which project outside the respirator, which congestion will occur due to the forcing of blood into the head if superatmos pheric pressures are used. One of the advantages of such pressures is that the rubber collar is pressed only towards shoulders where the veins in the neck are protected. Positive ressure forcing the collar toward the head is more objectionable.

Another advantage of this method of using negative pressures only is the resulting tendency to increase the normal chest expansion. In fact, substantial improvement of the chest expansion of patients has been obtained by this method; for example, a patient, formerly paralyzed, having a chest expansion of half an meh was improved by regular treatment in the respirator for 1 or 2 hours a day until after several weeks his voluntary chest expansion was an inch and a half.

The foregoing particular description is illustrative merely, but is not intended as delining the limits of the invention. It is obvious that various changes can be made in the construction and arrangement of the apparatus without departing from the spirit of the invention as defined in the appended claims.

1. An apparatus for prodiicing-artificial respiration comprising a substantially airti wh his head projecting out of said casing, means for periodically varying the pressure within the casing, and means ermitting access of an operators hands or manipulation within the casing while maintainin the periodic pressure variation, comprising a port, a flexible sealing sheet within said port having an aperture adapted to receive and to form an air-tight seal around the arm of the operator when inserted therein, and a cover arranged to close the port and to form an air-tight seal when the operators arm is not inserted in said ort.

p 2. An apparatus for producing artificial res iration comprising a substantially airtigllit casing to receive the body ofa patient with his head projecting out of said casing, means for periodically varying the pressure within the casing, and means permitting access of an operators hands for manipulation within the casing comprising a plurality of ports having apertures adapted to receive the arms of the operator, means in said apertures to form an air-tight seal around the operators arms when inserted therein, and means to seal said apertures in the plane of the casing wall when the operators arms are not inserted therein.

3. An apparatus for producing artificial re iration comprising a substantially airtig t casing to receive the body ofa patient with his head projecting out of said casing, means for periodically varying the pressure within the casing, and means permitting access of an operators hand for manipulation within the casing comprising a port adapted to receive the arm of the operator, means in said port to form an air-tight seal around the operators arm when inserted therein, and a flexible i'iap normally engaging the outer face of the sealing means to form an air-tight closure.

4. An apparatus for producing artificial respiration comprising a substantially airtight casing to receive the body of a patient with his head projecting out of said casing, means for periodically varying the pressure within the casing, and means permitting t casing to receive the body of a patient,

access of an operators hand for manipulation within the casing comprising an arm port,sealing means within said port adapted to forni a substantially air-tight seal around the arm of an operator when inserted therein, a second port adapted to permit the insertion of a bed pan or other article into the casing, said port being so positioned relative to the arm port as to permit the operator to grasp in his hand an article introduced through the second port, a cover closing said second port to form an air-tight seal and means to seal said arm port when the oierators arm is withdrawn.

5. n apparatus for producing artificial respiration comprising a substantially airtight casing to receive the body of a patient with his head projecting out of said casing, means for periodically varying the pressure within the casin and means permitting access of an operators hand for manipulation within the casing comprising a port having a sealing sheet with an aperture adapted to receive and to form an airtight seal around the arm of the o erator when inserted therein, and a liexibe flap normally engaging the outer face of the sealing sheet to form an air-tight closure together with a rigid hinged door arranged to close said port.

6. An. apparatus for producing artificial respiration comprising a casing to receive the body of a patient with his head projecting out of said casing, a body support for receiving the body of a patient, means for periodically varying the pressure within the easing, an aperture for receiving an enema tube through a wall of said casing and means for forming an air-tight seal around said tube together with an arm port iii a wallof said casing positioned to facilitate manipulation of said enema tube within the casing and means for forming an airtight s eal around the arm of an operator extending through the port.

7 An' apparatus for producing artificial respiration comprising a substantially airtight casing to receive the body of a patient with his head projecting out of said casing, means for periodically varying the pressure within the said casing, means permitting access of the operator for manipulation within the casing comprising a port adapted to receive the arm of the operator, with the bare h and extending within the casing, means in said aperture to form an air-tight seal around the operators arm when inserted therein and means to seal said aperture` when the operators arm is Withdrawn.

8. An apparatus for producing artificial respiration comprising a casing, a body support for receiving the body of a patient, means for periodically varying the pressure within the casing, an aperture for receiving respiration,

an enema tube through a wall of said casing and means for forming an air-tight seal around said tube together with an arm port in a wall ,of said casing, positioned to facilitate manipulation of said enema tube within the casing, and means for forming an air-tight .seal around the arm of an operator extending through the port, while the bare hand extends within the casing, for operation therein. v

9. In an apparatus for producing artificial respiration, a casing, means for periodically varying the pressure within the casing, a. body support for supporting the b ody ot the patient within the casing with his head projecting through the end wall thereof, means for forming an air-tight seal between the neck of the patient and the end wall comprising a iexible rubber collar adapted to clamp the same against the casing in adjusted position to form a comfortable fit around the patients neck and means to permit access of an operator within the casing while maintaining the periodic variations of pressure therein, comprising a port, a {iexible sealing means in said port havin an aperture adapted to receive a portion o the operators body and to form an air-tight seal around the same, and means to close said port when not in use. n

10. An apparatus for producingartificial respiration comprising a substantially airti ht casing to receive the body of a patient with his head projecting out of said casing, means for periodically varying the pressui-e within the casing and means permitting access of an operators hands f or manipulation Within the casing while niaintaining the periodic pressure variations, comprising a ort, a rubber sheet secured to the ed es 0 said port and projecting linwardly o said port and having ano ening therein to receive and form an air-tig t seal around the arm of the operator when inserted therein, and a cover arranged to close the port and to form an air-tight seal when the operators arm is not inserted in said ort. P 11. In apparatus for producing artificial a carriage, a casing arranged to receive the body of a patient with his mouth and nose exposed to the outer air, said casing being tiltably mounted on said carriage to permit varying the angle of inclination of the body of the patient, a cradle supporting the casing for lateral tilting, a pivotal mounting for said cradle to permit longitudinal tilting of the casing, a vertically adjustable supporting member at the foot end of the casing, a. pivotal connection between said member and the casing permitting lateral tilting of the casing, means to secure the supporting member in vertically adjusted position, means to secure the casing in its lateral tilted position, said casing having an inclined wall through which the head of the patient protrudes and means for periodically varying the pressure Within the casing to induce respiration.

12. In apparatus for producing artificial respiration, a carriage, a casin arranged to receive the body of a patient with his mouth and nose ex osed to the outer air, said casing being ti tably mounted on said carriage to permit varying the angle of inclination of the body of the patient, a cradle tiltable about a transverse axis between the ends of said casing in which said casing is mounted for lateral tilting movement, a vertically adjustable supporting member at one end of said casing to which said casing is pivotally connected for lateral tilting movement and means to secure said supporting member in adjusted position, means .to secure said casing in laterally tilted position and means for periodically varying the pressure Within the casing.

13. An apparatus for producing artificial respiration comprising a substantially airtight casing, to receive the body of a patient with his head projecting out of said casing, means for periodically varying the pressure within the said casing, means permitting access of the operator for manipulation within the casing comprising a port adapted to receive a portion of the operators body, sealing means in said port having an aperture to receive the inserted portion of t e operators body and form an air tight seal therearound and means for sealing the ort when the portion of the operators bo y is withdrawn.

14. An apparatus for producing artiicial res iration comprising a substantially airtig t casin to receive the body of a pa tient with is head proecting out of said casing, means for perio ically varying the pressure within the casing, and means permitting access of an operator for manipulation within the casing while maintaining the periodic pressure variation comprising a port, a exible sealing sheet within said port having an aperture permitting such access and adapted to form an air tight seal in the plane of the casing during such access and means arranged to close the port and to form an air-tight seal when the port is not in use, and means for periodically varying the pressure within the casing.

15. Apparatus for treatment of a patient comprising an air tight casing within which the air conditions differ from the external atmosphere, means permitting access of an operators hand for manipulation within the casing while maintaining the same air tight comprisin a port, a flexible sealing sheet within sai port having an aperture adapted to receive and form an air tight seal around the arm of the operator when inserted therein, and a cover arran ed to close the port and to form an air tig t seal when the operators arm is not inserted in said port.

In testimony whereof We have affixed our signatures to this ecification.

PHIL DRINKER. LOUIS AGASSIZ SHAW.

CERTIFICATE OF CORRECTION.

htent No. 1,906,844. May 2, 1933.

PHILIP DRINKER, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, lines 52, 66, and 86, claims 3, 4, and 5. respectively, for "hand" read hands; page 6, line 19, claim i9, after "to" insert the words fit closely around the neck of the patient, means around the edge of said collar to; and that the said Letters Patent should be read with these corrections therein that the same may.conform to the record lo! the case in the Patent Office.

Signed and sealed this 21st day of November, A. D. 1933.

F. M. Hopkins (Seal) Acting Commissioner of Patents.

the arm of the operator when inserted therein, and a cover arran ed to close the port and to form an air tig t seal when the operators arm is not inserted in said port.

In testimony whereof We have affixed our signatures to this ecification.

PHIL DRINKER. LOUIS AGASSIZ SHAW.

CERTIFICATE OF CORRECTION.

htent No. 1,906,844. May 2, 1933.

PHILIP DRINKER, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, lines 52, 66, and 86, claims 3, 4, and 5. respectively, for "hand" read hands; page 6, line 19, claim i9, after "to" insert the words fit closely around the neck of the patient, means around the edge of said collar to; and that the said Letters Patent should be read with these corrections therein that the same may.conform to the record lo! the case in the Patent Office.

Signed and sealed this 21st day of November, A. D. 1933.

F. M. Hopkins (Seal) Acting Commissioner of Patents. 

